This application claims priority based on French Application No. 02 06218, entitled xe2x80x9cExchanger For Aircraft Air Conditioning Circuit And Integrated Propulsion Assembly For Such An Exchangerxe2x80x9d by Herve Marche, filed on May 22, 2002, and which was not published in English.xe2x80x9d
1. Technical Domain
The invention mainly relates to a heat exchanger, intended to provide cooling of air introduced to an air conditioning circuit of an aircraft cabin.
More precisely, the invention relates to a heat exchanger integrated into a strut by which a turboreactor of an aircraft is suspended from the wing unit.
The invention also relates to an aircraft propulsion assembly, comprising a turboreactor, a strut and an exchanger integrated into the strut.
The invention is applied to any type of aircraft and especially to airliners intended for passenger transport.
2. Prior Art
On existing aircraft it is usual to draw off warm air in the turboreactors and then inject it into the air conditioning circuit of the pressurised cabin housing the crew and passengers.
Given that the air temperature drawn off in the reactor is generally around 400xc2x0 C., whereas the maximum temperature of the air circulating in the air conditioning circuit should not exceed around 200xc2x0 C., a heat exchanger is usually placed between the reactor and the air conditioning circuit. This exchanger ensures cooling of the air at high temperature originating from the reactor due to heat exchange between this air at high temperature and the colder air (at around 100xc2x0 C.) drawn off in the fan duct of the turboreactor.
Given that heat exchanges taking place inside the exchanger concern two flows of air issuing from the reactor, it is usual to place the exchanger in the immediate proximity of the latter. More precisely, the exchanger is usually integrated in the structure of the strut by which the reactor is suspended under the wing unit of the aircraft.
A known solution consists of mounting the exchanger above the front part of the caisson forming the rigid structure of the strut and inside the fairing covering said caisson.
In this case, the exchanger usually comprises vertical hollow plates between which relatively cold air originating from the exhaust manifold circulates from top to bottom, and is then ejected to the exterior, into the atmosphere, via ducts formed in the upper fairing of the strut. The relatively warm air originating from the central part of the engine circulates from front to rear inside the vertical hollow plates, to be cooled there before being channelled towards the air conditioning circuit. The relatively cold air originating from the exhaust manifold is introduced to the exchanger via tubing fitted with a valve allowing the flow to be regulated. Such regulation of the relatively cold air flow inside the exchanger enables the temperature of the air in the air conditioning circuit to be controlled.
Exchangers of this type have various disadvantages.
In the first place, implanting them above the front part of the rigid caisson of the strut would create swelling in the upper front part of the fairing, if this type of exchanger were used on an aircraft equipped with reactors larger in diameter than those which equipped it during design. Using reactors of larger diameter can especially be motivated by a desire to reduce the sound level and/or increase the performance of the aircraft, and in particular its speed. The resulting swelling would jeopardise the aerodynamic flow of air in the zone between the wing unit and the reactor. This is therefore unacceptable.
Another disadvantage of existing exchangers concerns releasing to the atmosphere the relatively cold air used to cool the air injected into the air conditioning circuit. This release to the atmosphere is practically imposed by circulation from bottom to top of the relatively cold air inside the exchanger, while the relatively moderate temperature of the rejected air would allow it to be used to cool certain warm parts of the engine.
The main aim of the invention is to provide an exchanger for cooling air introduced to an air conditioning circuit of an aircraft cabin, said exchanger being designed so as to be able to be installed in the very interior of the caisson of the strut, so as to avoid any risk of creating swelling when it is used on an aircraft equipped with reactors of larger diameter.
The invention also aims to provide an exchanger for cooling air introduced to an air conditioning circuit of an aircraft cabin, whereof the original design allows it to use the relatively cold air exiting from the exchanger for cooling the warm parts of the engine.
According to the present invention these aims are achieved, at least in part, due to an exchanger for cooling air, for an air conditioning circuit of an aircraft, said exchanger comprising an intake manifold and an exhaust manifold of relatively warm air, placed respectively in front of and behind the exchanger, and guides for relatively cold air, each having an inlet port and an outlet port, said guides delimiting between them passages connecting the intake manifold and the exhaust manifold, characterised in that the inlet ports and outlet ports of each guide of relatively cold air terminate on two opposite lateral faces of the exchanger, respectively on a front part and on a rear part of said lateral faces, the exchanger further comprising a first flow control door, placed on the front of each lateral face on which the inlet ports of the hollow plates terminate.
Accordingly, according to the present invention, the air used to cool the air injected into the air conditioning circuit of the aircraft circulates transversally in the exchanger, between its two lateral faces. It therefore becomes possible to place the exchanger right inside the rigid caisson of the strut, thus hypothetically avoiding the development of swelling where a reactor of larger diameter than that which originally equipped the aircraft would be used, at the time of design. On the other hand, this arrangement allows cooling air rejected by the exchanger to be used to cool certain warm parts of the engine.
According to a preferred embodiment of the invention, the guides for relatively cold air are superposed hollow plates, substantially horizontal.
In this case, the inlet ports of the hollow plates are preferably positioned alternatively in front of one and the other of said opposite lateral faces. This results in crossed circulation of the relatively cold air over the entire height of the exchanger.
The exchanger also comprises, advantageously, a second flow control door, placed on the rear part of each lateral face on which the outlet ports of the hollow plates terminate.
Another object of the invention is an aircraft propulsion assembly, comprising a turboreactor having a central engine and an engine nacelle delimiting between them a fan duct, a strut by which the reactor is designed to be suspended from a wing unit element of the aircraft, and an exchanger for cooling air, for an air conditioning circuit of an aircraft cabin, in which said exchanger is realised in the manner described hereinabove and placed in a strut in such a way that the outlet ports of air guides terminate in the fan duct of the turboreactor.